Topic
• 2 replies
• Latest Post - ‏2014-03-07T18:55:17Z by Kaouthar
Kaouthar
3 Posts

# Pinned topic CP Problem

‏2014-03-07T10:51:35Z | cplex

I'm still a beginner in CPLEX and I have a program which I want to model with the constraints and objective function.
I have a cloud architecture which contain J data center and each data center has a set of resources, and a set of requests and each request has its requirements.
To solve this problem, i created a boolean varibale y(ijk) which take 1 if the resource k in the center j can fit my request i and 0 otherwise. So  from the set of resource where the y(ijk)==1, i have to select the first site and the first resource to serve my request i. That's why i created two other boolean variable z(ij) which  take 1 if the center n° j is the first center and x(ijk) is equal to 1  if k is the the first resource of the first center j that fit my request. I chose for this this two constraints:
(j + 1) zij <= (s + 1)* yijk
(k + 1) xijk <= (r + 1) * yijk* zij. But in vain i coudn't select the adequate resource. Can someone help me please. Thank's in advance.

• PhilippeLaborie
153 Posts

#### Re: CP Problem

‏2014-03-07T13:39:14Z

Hello,

You say "Each application has a capacity and bandwidth and must be served by the first adequate resource". This seems to describe a selection rule to allocate the requests on the data centers/resources. If you need to follow this rule, your problem is not an optimization problem but simply a greedy algorithm applying this rule and you do not need CPLEX for that. You will need optimization if your allocation decisions are not (or at least are not completely) decided by this type of rule and if you want to use this freedom to optimize some criterion.

In any case, as your question is about a CPLEX model and not a CP one, I suggest you post your question on the Math Programming forum (Forum Directory >‎ IBM ILOG >‎ IBM ILOG Optimization >‎ Mathematical Programming).

Philippe

• Kaouthar
3 Posts

#### Re: CP Problem

‏2014-03-07T18:55:17Z

Hello,

You say "Each application has a capacity and bandwidth and must be served by the first adequate resource". This seems to describe a selection rule to allocate the requests on the data centers/resources. If you need to follow this rule, your problem is not an optimization problem but simply a greedy algorithm applying this rule and you do not need CPLEX for that. You will need optimization if your allocation decisions are not (or at least are not completely) decided by this type of rule and if you want to use this freedom to optimize some criterion.

In any case, as your question is about a CPLEX model and not a CP one, I suggest you post your question on the Math Programming forum (Forum Directory >‎ IBM ILOG >‎ IBM ILOG Optimization >‎ Mathematical Programming).

Philippe

No, i don't agree with you. The goal of the problem is to minimize the reject ratio.  In fact,  each request  must be served by the first center/resource that fit it and the opitmization will interfer in which requests will be accepted and whch will be rejected in order to obtain the minimum ration.